u - undoing the last change in command modeCtrl + r - Redo the last changeU - undo all fhe changes in the current line. (period) - Repeats last change in your cursor locations

yy - yanks (copy) a line (Similar to dd like delete equivalents) - the yanked texts goes to vi's buffer not to the OS clip-boardyw - yanks a word (just like dw deletes a word)p - pastes the yanked text after the cursorP - pastes the yanked text before the cursor